/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.el;

import org.apache.el.lang.ELSupport;
import org.apache.el.util.MessageFactory;
import org.apache.el.util.ReflectionUtil;

import javax.el.ELContext;
import javax.el.PropertyNotWritableException;
import javax.el.ValueExpression;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

public final class ValueExpressionLiteral extends ValueExpression implements
		Externalizable {

	private static final long serialVersionUID = 1L;

	private Object value;

	private Class<?> expectedType;

	public ValueExpressionLiteral() {
		super();
	}

	public ValueExpressionLiteral(Object value, Class<?> expectedType) {
		this.value = value;
		this.expectedType = expectedType;
	}

	@Override
	public Object getValue(ELContext context) {
		if (this.expectedType != null) {
			return ELSupport.coerceToType(this.value, this.expectedType);
		}
		return this.value;
	}

	@Override
	public void setValue(ELContext context, Object value) {
		throw new PropertyNotWritableException(MessageFactory.get(
				"error.value.literal.write", this.value));
	}

	@Override
	public boolean isReadOnly(ELContext context) {
		return true;
	}

	@Override
	public Class<?> getType(ELContext context) {
		return (this.value != null) ? this.value.getClass() : null;
	}

	@Override
	public Class<?> getExpectedType() {
		return this.expectedType;
	}

	@Override
	public String getExpressionString() {
		return (this.value != null) ? this.value.toString() : null;
	}

	@Override
	public boolean equals(Object obj) {
		return (obj instanceof ValueExpressionLiteral && this
				.equals((ValueExpressionLiteral) obj));
	}

	public boolean equals(ValueExpressionLiteral ve) {
		return (ve != null && (this.value != null && ve.value != null && (this.value == ve.value || this.value
				.equals(ve.value))));
	}

	@Override
	public int hashCode() {
		return (this.value != null) ? this.value.hashCode() : 0;
	}

	@Override
	public boolean isLiteralText() {
		return true;
	}

	@Override
	public void writeExternal(ObjectOutput out) throws IOException {
		out.writeObject(this.value);
		out.writeUTF((this.expectedType != null) ? this.expectedType.getName()
				: "");
	}

	@Override
	public void readExternal(ObjectInput in) throws IOException,
			ClassNotFoundException {
		this.value = in.readObject();
		String type = in.readUTF();
		if (!"".equals(type)) {
			this.expectedType = ReflectionUtil.forName(type);
		}
	}
}
